A system called a thin client is known. Thin client systems are configured so that a client terminal is provided with only a minimum of functions and resources, such as applications, files, and the like, are managed by a server.
In a thin client system, the client terminal acts as if the client terminal actually executes processes and stores data although it is in fact the server that makes the client terminal display results of processes executed by the server or data stored in the server.
When transmitting, between the server and the client terminal, screen data that is displayed on the client terminal, an update of a screen occurs due to an operation. If the update of the screen occurs in the thin client system, screen data that indicates a difference of the screen between before and after the update is sent from the server to the client terminal. At this point, if a rotating operation is performed on an object by using, for example, three Dimensional-Computer Aided Design (3D-CAD) or the like, an update occurs in many parts in the screen and screen data related to the difference is sent to the client terminal at a time.
Patent Document 1: Japanese Laid-open Patent Publication No. 2008-210113
Patent Document 2: Japanese Laid-open Patent Publication No. 2002-26986
However, with the technology described above, a transmission delay may sometimes occur.
For example, if the update occurs in many portions of the screen, screen data related to the difference is sent to the client terminal at a time. Specifically, the screen data on the difference is sent to the client terminal as burst transmission in a predetermined time period. Accordingly, in a network between the server and the client terminal, an amount of the traffic exceeds the throughput of network devices and thus a packet loss occurs. Consequently, a transmission delay occurs due to a resend of a packet and a display update speed of the display may sometimes be reduced.